'66 Dart kick down diagram
There were several changes over the years for different reasons. I think 66 did have the safe throttle return slot in that first rod. Earlier models didn't have that safety feature.
In 66 the bell crank was still mounted on the back end of the head. There were problems related to that also. I'm not sure if all those bell cranks moved up on top of the intake in the same year but it is a better design ( fewer faults ).
At the same time mix matched parts rarely work right so...
Gather any complete throttle pressure setup, use it no matter which year design it is.